What is Hide Glue?

If you are a woodworker or a DIY enthusiast, you have probably heard of hide glue. This type of adhesive has been used for centuries, and it is still popular among professionals and hobbyists alike. But what exactly is hide glue, and why is it so special?

Hide glue is a type of adhesive made from animal hides, bones, and connective tissues. The most common source of hide glue is the collagen found in animal skins. The process of making hide glue involves soaking the hides and other materials in water, then boiling them to extract the collagen. The resulting liquid is then filtered, purified, and dried to produce a granular or powder form of glue.

Hide glue is considered a natural and organic adhesive because it is made from renewable resources and does not contain any synthetic chemicals. In this article, we will explore the advantages and disadvantages of hide glue, its uses, and how to use and make it.

Liquid Hide Glue vs Hot Hide Glue

Compared to hot hide glue that cures hard, liquid hide glue sets with a slight flexibility, making it a versatile adhesive in woodworking. Liquid hide glue, also known as animal glue, is made from the protein collagen that’s extracted from animal hides, bones, and connective tissues.

This type of glue has a longer setting time compared to hot hide glue, allowing woodworkers to work on intricate glue joints without the fear of the glue setting too quickly. Here are some differences between liquid hide glue and hot hide glue that woodworkers should keep in mind:

• Liquid hide glue remains somewhat flexible after it sets, while hot hide glue cures hard.
• Liquid hide glue has a longer open time than hot hide glue, giving woodworkers more time to adjust and reposition their work.
• Liquid hide glue has a slightly weaker strength than hot hide glue, but it’s still stronger than the wood itself.

Advantages of Hide Glue

One of the best things about hide glue is its reversibility, allowing for disassembly of joints without damaging the wood. This is particularly advantageous for furniture makers who need to make repairs or modifications to their pieces without compromising their integrity.

Hide glue is made from the collagen of animal hides, and its unique properties allow it to bond strongly with wood fibers, creating joints that are as strong as those made with modern synthetic glues. In addition to its reversibility, hide glue has other advantages that make it a popular choice among woodworkers.

Its long open time and lubricating properties make it easy to work with, allowing for precise fitting of joints. It also creates close to invisible joints, making it ideal for veneering. Hide glue is available in multiple grades, providing progressively longer open times, and can even be extended by adding salt.

Its ability to bond with old hide glue also makes it a reliable choice when regluing joints. Overall, hide glue is a versatile and reliable adhesive that has been used by woodworkers for centuries.

Disadvantages of Hide Glue

Despite its advantages, hide glue isn’t without its drawbacks. One major disadvantage is its susceptibility to failure when exposed to water-based finishes. This is because water-based finishes can soften the hide glue joints, causing them to weaken and eventually fail over time. It’s important to note that hot hide glue is less likely to be affected by water-based finishes, but liquid hide glue can be more susceptible to failure.

Another disadvantage of hide glue is the preparation time required before glue-up. The glue must be mixed exactly to manufacturer specifications for different open times, and it requires heating before it can be used. In addition, the temperature of the glue, the shop, and the workpieces need to be monitored for optimum glue-up conditions. Failure to do so can result in a weakened joint or a shortened shelf life for the glue.

Lastly, high humidity can also weaken joints made with liquid hide glue. Overall, while hide glue has many advantages, it’s important to understand and address its potential disadvantages to ensure successful use.

What is Hide Glue Used For

Hide glue, also known as animal or collagen glue, is a type of woodworking glue that has been used for centuries. It’s made from boiling down animal hides and bones to create a strong, natural adhesive.

Hide glue is a preferred adhesive for luthiers, antique conservators, and traditional woodworkers due to its unique properties. It provides a strong bond and can be easily repaired or reversed if needed, making it a popular choice for delicate projects such as musical instruments. Unlike modern synthetic adhesives, hide glue can fail over time if exposed to high humidity or extreme temperatures. However, this can be mitigated by properly storing and using the glue.

Hide glue is also known for its ability to be disassembled and repositioned by heating it to 145º, making it a versatile choice for complex woodworking projects. Its ability to not clog tools or sandpaper and to be used for rub joints without clamps and hammer veneering without clamps make it a popular choice among woodworking professionals.

How to Use Hide Glue

To properly use hide glue, you’ll need to first heat it up in a glue pot to a temperature of around 135°–145°. This temperature range usually takes about 30 minutes to reach, and it’s essential to maintain the glue’s liquid form.

Once you’ve heated the glue, spread it onto both surfaces to be joined using a bristle brush. The glue’s open time is relatively short, so work quickly to avoid it starting to gel.

To achieve a strong bond, apply the glue to both surfaces and then immediately rub them together to work out any air bubbles and create a tight fit. Be aware that hide glue has an initial tack, so it’s essential to align the pieces correctly before the glue sets.

Once you’ve aligned the pieces, clamp them together and allow the glue to dry. Hide glue can take up to several hours to dry, depending on the ambient temperature.

After the glue has dried, wipe off any excess glue with a wet cloth.

Where to Buy Hide Glue

You can easily find hide glue options at your local woodworking or craft store, or even purchase glue crystals online to make your own hot hide glue at home.

1. Hardware stores: Many hardware stores carry hide glue products, both in liquid and crystal form. Look for brands such as Titebond, Old Brown Glue, or Franklin International.
2. Online retailers: You can find a wide variety of hide glue products online, from glue crystals to pre-made liquid hide glue. Some popular online retailers include Amazon, Woodcraft, and Rockler.
3. Specialty woodworking stores: If you’re looking for a wider variety of hide glue options, check out specialty woodworking stores. They may carry different strengths of hide glue, as well as synthetic adhesives and other materials for woodworking and veneer work.

How to Make Hide Glue

Hide glue is a type of adhesive made from animal connective tissue, usually from cows or horses. Its use dates back to ancient times, where it was used for woodworking and bookbinding. Today, hide glue is still used in woodworking for its strong bond and ability to be easily reversed with heat and moisture.

To make hide glue, you’ll need to first soak the animal connective tissue in water for several hours or overnight. Once softened, it’s then boiled for a prolonged period of time, usually around 12-24 hours, until it turns into a thick, gelatinous substance. The mixture is then strained to remove any impurities and can be used immediately while still hot, or cooled to room temperature and stored as a liquid hide wood glue.

It’s important to note that different types of animal connective tissue can produce different strengths of glue. For example, bone glue is known for its high strength, while skin glue is weaker.

Hide Glue vs Wood Glue

When deciding between adhesives for woodworking projects, it’s important to consider the specific needs of your project. Two common options are hide glue and wood glue, each with their own strengths and weaknesses:

1. Strength and durability: Hide glue is a great choice for delicate restoration projects or instrument-making, but it may not hold up as well under heavy stress. Wood glue, on the other hand, is designed for maximum strength and durability, making it a better option for projects that will be subject to wear and tear.
2. Assembly time: Hide glue requires a longer assembly time than wood glue, as it needs to be heated in a pot before use. This can be both an advantage and a disadvantage; while it allows for more flexibility during the assembly process, it may also make the process more time-consuming.
3. Appearance: Hide glue is often preferred for restoration projects, as it dries clear and can be easily reversed if needed. However, it may not be the best choice for projects where appearance is a concern, as it can dry to a brownish color. Wood glue, on the other hand, can be sanded and stained to match the surrounding wood, making it a better choice for visible joints.

Ultimately, the choice between hide glue and wood glue depends on your project’s specific needs.

Conclusion

Hide glue has been used for centuries and is a popular choice among woodworkers for its strong bond and ability to be easily repaired. When using hide glue, it’s important to remember that it has a shorter open time than other wood glues, so it’s essential to work quickly. Additionally, it requires a bit more preparation and cleanup than other glues, but the end result is worth the extra effort.

Overall, hide glue is a versatile and reliable adhesive that has stood the test of time. Whether you’re a professional woodworker or a DIY enthusiast, adding hide glue to your toolbox is definitely worth considering.

Frequently Asked Questions

Is hide glue safe to use for food-related projects, such as cutting boards or utensils?

You should not use hide glue for food-related projects. Although traditionally used in woodworking, hide glue can potentially harbor bacteria and is not considered food-safe.

Can hide glue be used for outdoor projects that will be exposed to the elements?

Yes, hide glue can be used for outdoor projects, but it is important to note that it is not as resistant to moisture as modern adhesives. It is best to use it in combination with other waterproofing techniques.

How long does it take for hide glue to dry and set?

Hide glue typically takes around 30 minutes to an hour to dry, depending on the temperature and humidity. It will then continue to set over the course of several hours, with a full cure time of 24 hours.

Is hide glue the same as animal glue?

Yes, hide glue is a type of animal glue. Both terms are often used interchangeably.

Are animals killed for hide glue?

Hide glue is typically made from the byproducts of animals that are slaughtered for other purposes, such as for meat. The animals are not typically killed for the sole purpose of producing glue; instead, the glue is made from materials that would otherwise go to waste.